Field
Aspects of the present invention generally relate to a power supply device, a power supply method, and a program.
Description of the Related Art
Conventionally, a technology for supplying power in a non-contact (wireless) manner exists. As a non-contact power supply system, there are four systems described below. That is, an electromagnetic induction system, a magnetic field resonance system, an electric field coupling system, and a radio wave reception system. Among them, the magnetic field resonance system can transmit sufficient power to a long distance as its feature. Thus, the magnetic field resonance system has particularly drawn attention among the four systems. In the magnetic field resonance system, a 1 to N power supply system has been discussed which utilizes the long power transmission distance. In the 1 to N power supply, a power transmission device wirelessly transmits power to a plurality of reception devices (for example, see Japanese Patent Application Laid-Open No. 2009-136132).
According to the technology of Japanese Patent Application Laid-Open No. 2009-136132, the power transmission device transmits a fixed pulse signal in a stand-by mode, when the power transmission device are not transmitting power, to find whether a power reception device is present in its proximity within a several meters. When the reception device transmits its own unique identification (ID) to the power transmission device, the power transmission device determines whether a transmission source of the unique ID is a power reception device as a power supply target. When the power reception device is the power supply target, the power transmission device supplies the power to the power reception device. At this time, the power transmission device can transmit a unique code to the power reception device so that the power transmission device individually receives a charge amount, a state of the device, and the like by.
When a processing period for confirming whether the power reception device wishes to receive power is over, the power transmission device starts to supply the power to the power reception device, which has been determined as a power transmission destination. During a period in which the power transmission device supplies the power, the power transmission device cannot receive a power reception request from other power reception devices.
For example, assume that a first power reception device needs to be immediately charged due to reduction in a battery residual capacity, and the like.
Further, suppose that, at this time, the power transmission device is in the middle of supplying the power to a second power reception device. In this case, there is a problem that the power transmission device cannot supply the power to the first power reception device until the power supply period for supplying the power to the second power reception device is over.